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II. The Living World
A. Ecosystem Structure
Biological populations and communities; ecological niches;
interactions among species; keystone species; species diversity and
edge effects; major terrestrial and aquatic biomes
B. Energy Flow
Photosynthesis and cellular respiration; food webs and trophic
levels; ecological pyramids
C. Ecosystem Diversity
Biodiversity; natural selection; evolution; ecosystem services
D. Natural Ecosystem Change
Climate shifts; species movement; ecological succession
E. Natural Biogeochemical Cycles
Carbon, nitrogen, phosphorus, sulfur, water, conservation of matter
THE NATURE OF ECOLOGY

Ecology is a study of
connections in nature.

How organisms
interact with one
another and with their
nonliving
environment.
Figure 3-2
Species Diversity and Niche
Structure: Different Species Playing
Different Roles

Species diversity: the number of different species it
contains (species richness) combined with the
abundance of individuals within each of those species
(species evenness).
Indicator Species:
Biological Smoke Alarms
-early warnings of damage
to a community or an
ecosystem.
Ex. Presence or absence of
trout species because they are
sensitive to temperature and
oxygen levels.
Keystone Species: Major Players
-determine the types and numbers of other
species in a community, helping to sustain
it.
Figures 7-4 and 7-5
Foundation Species:
Other Major Players
-can create and enhance
habitats which benefits other
species in a community.
Ex. Elephants push over,
break, or uproot trees, creating
forest openings promoting
grass growth for other species
to utilize.
Population
-A group of the same species living
w/in a particular area.
Community
-All the population s in an area.
Ecosystem
- All nonliving
(abiotic) and
living (biotic)
components
Universe
Galaxies
Solar systems
Biosphere
Planets
Earth
Biosphere
Ecosystems
Ecosystems
Communities
Populations
Realm of ecology
Organisms
Organ systems
Communities
Organs
Tissues
Cells
Populations
Protoplasm
Molecules
Atoms
Organisms
Subatomic Particles
Fig. 3-2, p. 51
Habitat

The place where an organism or a
population lives.
Niche


The total way of life or role of a
species in an ecosystem.
All the physical, chemical, and
biological conditions a species needs
to live & reproduce in an ecosystem.
Species Interactions:Symbiosis
Parasitism –when 1 species (parasite)
feeds on part of another species (host) by
living on or in it
Commensalism – benefits one species
but doesn't harm or help the other
Mutualism – both species benefit
Parasites: Sponging Off of Others

Although parasites can harm their hosts,
they can promote community biodiversity.
Some parasites live in host (micororganisms,
tapeworms).
 Some parasites live outside host (fleas, ticks,
mistletoe plants, sea lampreys).
 Some have little contact with host (dumpnesting birds like cowbirds, some duck species)

Mutualism: Win-Win Relationship

Two species
can interact in
ways that
benefit both of
them.
Figure 7-9
Commensalism: Using without Harming
-helps one species
but has little or no
effect on the
other.
Figure 7-10
Predator

An organisms that captures & feeds on
parts or all of another animal.
Prey

An organisms that is captured & serves
as a source of food for another animal.
Cycle

See graph (page 203 and 204)
Decomposition
-When organisms die
or release waste
Bacteria break down
and return the
chemicals back to the
soil.
BIOMES:
CLIMATE AND LIFE ON LAND
Figure 5-9
BIOMES:
CLIMATE AND LIFE ON LAND

Biome type is determined by precipitation,
temperature and soil type
Figure 5-10
Photosynthesis
Producers: Basic Source of All Food
producers capture sunlight to produce
carbohydrates by photosynthesis:
First Trophic
Level
Second Trophic
Level
Third Trophic
Level
Producers
(plants)
Primary
consumers
(herbivores)
Secondary
consumers
(carnivores)
Heat
Heat
Fourth Trophic
Level
Tertiary
consumers
(top carnivores)
Heat
Solar
energy
Heat Heat
Heat
Heat
Heat
Detritivores
(decomposers and detritus feeders)
Fig. 3-17, p. 64
Food Webs/Chains
-how energy & nutrients
move through the
ecosystem
Arrows – point from the
producer to the
consumer
Energy Flow in an Ecosystem:
Losing Energy in Food Chains and
Webs

Ecological
efficiency:
percentage of
useable energy
from one trophic
level to the next.
Figure 3-19
10% Rule



We assume that 90% of the energy at each
energy level is lost because the organism
uses the energy. (heat)
It is more efficient to eat lower on the
energy pyramid. You get more out of it!
This is why top predators are few in number
& vulnerable to extinction.
Producers
-use photosynthesis or chemosynthesis (some
bacteria) to manufacture its food.
Primary Consumer (herbivore)
-feed directly on all
or parts of plants.
Secondary Consumer
(carnivore)
-feed only on
primary
consumers. Most
are animals, but
some are plants
(Venus fly-trap).
Tertiary Consumer (carnivore)
-feed on animaleating animals. Ex.
hawks, lions, bass,
and sharks.
Quaternary Consumer (carnivore)
-feeds on tertiary
consumers. Ex.
humans.
Decomposers and Detrivores
Decomposers: Recycle nutrients in ecosystems.
 Detrivores: Insects or other scavengers that feed on
wastes or dead bodies.

Figure 3-13
Biodiversity
-the many forms of life
found on the Earth.
“Wildness”


Genetic Diversity – the
variety of genetic makeup w/in a single species
Species Diversity – the
variety of species in
different habitats on the
Earth
Biological
Evolution
-has led to the
variety of
species we find
on the earth
today.
Figure 4-2
EVOLUTION, NATURAL
SELECTION, AND
ADAPTATION
- the change in a population’s genetic
makeup through successive generations.


genetic variability
Mutations: random changes in the DNA that
can be inherited by offspring.
Succession
-process where plants & animals of a
particular area are replaced by other more
complex species over time.
Primary Succession
-begins with a lifeless area where there is no soil
(ex. bare rock). Soil formation begins with lichens
or moss.
Stages

Land – rock  lichen  small shrubs 
large shrubs  small trees  large trees
Water – bare bottom  small/few
underwater vegetation  temporary pond
and prairie  forest and swamp
Secondary succession - begins where the
natural community has been disturbed, removed,
or destroyed, but soil or bottom sediments
remain.
Pioneer Communities

Lichens and moss.
Climax Communities
-area dominated by a few, long-lived
plant species.
Biosphere
Carbon
cycle
Phosphorus
cycle
Nitrogen
cycle
Water
cycle
Oxygen
cycle
Heat in the environment
Heat
Heat
Heat
Fig. 3-7, p. 55
CARBON CYCLE
Effects of Human Activities
on Carbon Cycle
-We add excess CO2 to
the atmosphere
through:
Burning fossil fuels.
 Clearing vegetation
faster than it is
replaced.

Figure 3-28
Phosphorous Cycle
Effects of Human Activities
on the Phosphorous Cycle
1. We remove large amounts of phosphate
from the earth to make fertilizer.
2. We reduce phosphorous in tropical soils by
clearing forests.
3. We add excess phosphates to aquatic
systems from runoff of animal wastes and
fertilizers.
Nitrogen Cycle
Effects of Human Activities
on the Nitrogen Cycle
1.
2.
Adding gases that contribute to acid rain.
Contaminating ground water from nitrate
ions in inorganic fertilizers.
Nitrogen Fixation
- bacteria convert N2 gas to ammonia (NH3)
that can be used by plants.
Nitrification
- Ammonia is converted to nitrite (NO2), then
to nitrate(N03)
Assimilation
- Plants use N02 and NO3 to make DNA,
amino acids and proteins.
Ammonification
- decomposing bacteria convert wastes, and
dead bodies into ammonia.
Denitrification
-Nitrate ions and nitrite ions are converted into
nitrous oxide gas and nitrogen gas by
denitrifying bacteria
The Sulfur Cycle
Figure 3-32
Effects of Human Activities
on the Sulfur Cycle

We add sulfur dioxide to the atmosphere by:
Burning coal and oil
 Refining sulfur containing petroleum.
 Convert sulfur-containing metallic ores into
free metals such as copper, lead, and zinc
releasing sulfur dioxide into the environment.

Water cycle